The 38-year-old model mogul was just beginning her modeling days when her body changed from a size four to a size six, prompting hate mail and charges made by designers that she was fat and not hire-able.

"My mom said, 'You know what, we're going to do about this? We're going to go get pizza,'" Banks said today on " Good Morning America." "And over pizza in a Milan pizzeria we crafted a strategy for how to take my curves and make them work for me as opposed to me either starving myself or bowing out of the modeling industry."

Banks, of course, went on to become one of the world's top supermodels, earning millions of dollars, posing in countless magazines and turning her modeling fame into a business empire.

She also stood out as a critic of the fashion and media industries' focus on weight, famously appearing in a bathing suit on TV and telling critics to "kiss my fat a**" after Australian tabloids published unflattering photos and said she'd gained 40 pounds.

Now, in an open letter addressed to "models around the world," the model-turned-mogul is applauding Vogue for its boldness in addressing what she calls the fashion industry's "unspoken rule" that skinny is OK.

"Real progress is finally on the horizon," Banks writes in the letter, posted on the Daily Beast website. " Vogue is stepping up, doing the right thing, and protecting that girl. Perhaps that girl is you!"

In the move announced earlier this month by Vogue publisher Conde Nast International, the leading fashion trade's 19 worldwide editors signed a six-point pact to project the image of healthy models by, among other things, "not knowingly work with models under the age of 16 or who appear to have an eating disorder," and asking casting directors to check IDs at photo shoots and fashion shows and for ad campaigns.

"When a girl is looking at a magazine with her mother, there are these subliminal images saying if you're not a size zero, if you don't look exactly like this, you're not good enough,'" Banks said on "GMA." "So the fact that Vogue is making that mandate is the beginning of something huge."

In the years since that career-changing huddle with her mom over pizza, Banks has hosted her own, eponymous talk show, authored a fiction novel, earned her MBA from Harvard and created and hosted the popular runway reality-TV competition show "America's Next Top Model," where she has made a point of promoting healthy figures among her models.

"I've existed in this bubble," Banks said of her work on the show. "And I have had to say, 'OK, these are my girls in this bubble.' But then they leave 'Top Model' and, if they're not a size zero, they're not going to work.

"I actually mentor a whole bunch of girls that are in the fashion industry that work for Vogue all over the world, and other magazines," she said. "They're like, 'I'm at the top of my game, Tyra, I'm now 19 (or 20, 21) and my body is changing. I'm maturing. I'm still eating the same thing but things are changing and I'm not getting as many fashion shows. My agency tells me that I'm now a two and I need to be a zero and they're firing me."

"Now I love that I'm not going to be getting that call as much about, 'Oh, my God, Tyra, I'm hungry. I'm starving. What the hell do I do?,'" she said.

Banks says that as much as the Vogue pact will help the models, she's equally excited for what it will do for the young girls who look in the pages of fashion magazines.

"Little girls are looking at these things and it's so important for their mothers to explain to them that things are retouched, that these girls are not necessarily eating healthily," she said. "That girl needs to close that magazine and her mom needs to help her with her self esteem to say she's good enough.

"I'm using a word right now called 'flawesome,'" she added. "That means you plus your flaws are awesome, and equals 'flawesome.'"